Toxicity, endpoint

Toxic endpoint Assessment metric Measurement metric... 

The current version of eChemPortal offers the possibility to retrieve information by searching on chemical names or CAS Registry numbers. The second phase will incorporate additional search options to retrieve and compile specific hazard or other effects data (e.g., toxicity endpoints) from the participating databases. 

The results from using the Student s f-test for a distributional analysis are presented in Table 4. These results indicate the probability of a given worker in the listed scenario exceeding the NOEL of the toxicity endpoint. The probability of exceeding the LOEL and of thus experiencing a depression of plasma cholinesterase activity is not given (except for chronic exposure scenarios in the "100 ug/kg bw/day" column). Hence, even these probabilities may be considered to be conservative and not fully representative of the probability of a worker actually experiencing a toxic effect. 

TEST allows for estimates of the value for several toxicity endpoints [29] 96 h Fathead minnow LC50, 48 h Daphnia magna LC50, 48 h Tetrahymena pyriformis IGC50, Oral rat LD50, bioaccumulation factor, developmental toxicity, and Ames mutagenicity. TEST also estimates several physical properties... 

ACD/Tox Suite is a collection of software modules that predict probabilities for basic toxicity endpoints. Predictions are made from chemical structure and based upon large validated databases and QSAR models, in combination with expert knowledge of organic chemistry and toxicology. ToxSuite modules for Acute Toxicity, Genotoxicity, Skin Irritation, and Aquatic Toxicity have been used. 

Quantitative Structure-Activity Relationship studies search for a relationship between the activity/toxicity of chemicals and the numerical representation of their structure and/or features. The overall task is not easy. For instance, several environmental properties are relatively easy to model, but some toxicity endpoints are quite difficult, because the toxicity is the result of many processes, involving different mechanisms. Toxicity data are also affected by experimental errors and their availability is limited because experiments are expensive. A 3D-QSAR model reflects the characteristics of... 

The AEGL values and toxicity endpoints are summarized in Table 1-11. Because aniline is absorbed through the skin, a skin notation was added to the table of values. 

SUMMARY OF PROPOSED AEGLS 8.1. AEGL Values and Toxicity Endpoints... 

Acute lethality data for inhalation exposure to monomethylhydrazine are available for monkey, dog, rat, mouse, and hamster. Based upon the available data, hamsters appear to be the most resistant species, and the squirrel monkey and beagle dog are the most sensitive. The lethality of monomethylhydrazine appeared to follow a linear relationship for exposures up to 1 h. Most animal data focus on lethality as the toxicity endpoint with very limited exposure-response information available regarding nonlethal effects. The most significant effect reported in the acute exposure studies was the notable hemolytic response that was reversible upon cessation of exposure. However, the preponderance of the data suggest that there is little margin between exposures associated with nonlethal, reversible effects and those that result in death. 

Toxicity endpoint AEGL-2 values were based upon a 3-fold reduction in the AEGL-3 values. This estimate of a threshold for irreversible effects was justified because of the absence of exposure-response data related to irreversible or other serious, long-lasting effects and the steep dose-response relationship indicated by the data that was available on monomethylhydrazine... 

Toxicity endpoint 1-h LC50 of 82 ppm in female squirrel monkeys lethality threshold estimated as a 3-fold reduction of the LC50 (82 ppm/3=27.3 ppm)... 

Key study Toxicity endpoint Weeks et al. 1963 Dogs exposed to 1,1-dimethylhydrazine at 360 ppm for 15 min exhibited behavioral changes and muscle fasciculations... 

Key study Toxicity endpoint Weeks et al. 1963 1-h LC50 of 981 ppm in dogs reduced by a factor of three to 327 ppm as an estimate of a lethality threshold. Weeks et al. (1963) provided data showing that 15-min exposure of dogs at 36 100 ppm produced only minor, reversible effects (behavioral changes and mild muscle fasciculations)... 

Table 5-8 Toxic Endpoints Specified by the EPA Risk Management Plan1...

Chemical name Toxic endpoint (mg/L) Chemical name Toxic endpoint (mg/L)... 

The EPA Risk Management Plan (RMP) defines a worst-case scenario as the catastrophic release of the entire process inventory in a 10-min period (assumed to be a continuous release). The dispersion calculations must be completed assuming F stability and 1.5 m/s wind speed. As part of the RMP rule, each facility must determine the downwind distance to a toxic endpoint. These results must be reported to the EPA and to the surrounding community. 

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